title: Chinese hamster ovary cell mutants defective in the internalization of ricin.
abstract: Chinese hamster ovary mutants simultaneously resistant to ricin and Pseudomonas toxin have been isolated. Two mutant cell lines (4-10 and 11-2) were found to retain normal levels of binding of both ricin and Pseudomonas toxin. They were defective in the internalization of [125I]ricin into the mutant cells, as measured by both a biochemical assay for ricin internalization and electron microscopic autoradiographic studies. Although pretreatment of Chinese hamster ovary cells with a Na+/K+ ionophore, nigericin, resulted in an enhancement of the cytotoxicities of ricin and Pseudomonas toxin in the wild-type Chinese hamster ovary cells, preculture of the mutant cells did not alter the susceptibility of the mutant cells to either toxin. These results provide further evidence that there is a common step in the internalization process for ricin and Pseudomonas toxin.
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured / Q000187:drug effects*; D006224:Cricetinae; D003412:Cricetulus; D004167:Diphtheria Toxin / Q000494:pharmacology; D005260:Female; D009154:Mutation; D009550:Nigericin / Q000494:pharmacology; D010053:Ovary; D011550:Pseudomonas aeruginosa; D011955:Receptors, Drug / Q000378:metabolism; D012276:Ricin / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D001427:Bacterial Toxins; D004167:Diphtheria Toxin; D011955:Receptors, Drug; D012276:Ricin; D009550:Nigericin